thirdparty/freetype-2.3.12/src/gzip/infcodes.c

   1 /* infcodes.c -- process literals and length/distance pairs
   2  * Copyright (C) 1995-2002 Mark Adler
   3  * For conditions of distribution and use, see copyright notice in zlib.h
   4  */
   5
   6 #include "zutil.h"
   7 #include "inftrees.h"
   8 #include "infblock.h"
   9 #include "infcodes.h"
  10 #include "infutil.h"
  11
  12 /* simplify the use of the inflate_huft type with some defines */
  13 #define exop word.what.Exop
  14 #define bits word.what.Bits
  15
  16 typedef enum {        /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
  17       START,    /* x: set up for LEN */
  18       LEN,      /* i: get length/literal/eob next */
  19       LENEXT,   /* i: getting length extra (have base) */
  20       DIST,     /* i: get distance next */
  21       DISTEXT,  /* i: getting distance extra */
  22       COPY,     /* o: copying bytes in window, waiting for space */
  23       LIT,      /* o: got literal, waiting for output space */
  24       WASH,     /* o: got eob, possibly still output waiting */
  25       END,      /* x: got eob and all data flushed */
  26       BADCODE}  /* x: got error */
  27 inflate_codes_mode;
  28
  29 /* inflate codes private state */
  30 struct inflate_codes_state {
  31
  32   /* mode */
  33   inflate_codes_mode mode;      /* current inflate_codes mode */
  34
  35   /* mode dependent information */
  36   uInt len;
  37   union {
  38     struct {
  39       inflate_huft *tree;       /* pointer into tree */
  40       uInt need;                /* bits needed */
  41     } code;             /* if LEN or DIST, where in tree */
  42     uInt lit;           /* if LIT, literal */
  43     struct {
  44       uInt get;                 /* bits to get for extra */
  45       uInt dist;                /* distance back to copy from */
  46     } copy;             /* if EXT or COPY, where and how much */
  47   } sub;                /* submode */
  48
  49   /* mode independent information */
  50   Byte lbits;           /* ltree bits decoded per branch */
  51   Byte dbits;           /* dtree bits decoder per branch */
  52   inflate_huft *ltree;          /* literal/length/eob tree */
  53   inflate_huft *dtree;          /* distance tree */
  54
  55 };
  56
  57
  58 local inflate_codes_statef *inflate_codes_new( /* bl, bd, tl, td, z) */
  59 uInt bl, uInt bd,
  60 inflate_huft *tl,
  61 inflate_huft *td, /* need separate declaration for Borland C++ */
  62 z_streamp z )
  63 {
  64   inflate_codes_statef *c;
  65
  66   if ((c = (inflate_codes_statef *)
  67        ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL)
  68   {
  69     c->mode = START;
  70     c->lbits = (Byte)bl;
  71     c->dbits = (Byte)bd;
  72     c->ltree = tl;
  73     c->dtree = td;
  74     Tracev((stderr, "inflate:       codes new\n"));
  75   }
  76   return c;
  77 }
  78
  79
  80 local int inflate_codes( /* s, z, r) */
  81 inflate_blocks_statef *s,
  82 z_streamp z,
  83 int r )
  84 {
  85   uInt j;               /* temporary storage */
  86   inflate_huft *t;      /* temporary pointer */
  87   uInt e;               /* extra bits or operation */
  88   uLong b;              /* bit buffer */
  89   uInt k;               /* bits in bit buffer */
  90   Bytef *p;             /* input data pointer */
  91   uInt n;               /* bytes available there */
  92   Bytef *q;             /* output window write pointer */
  93   uInt m;               /* bytes to end of window or read pointer */
  94   Bytef *f;             /* pointer to copy strings from */
  95   inflate_codes_statef *c = s->sub.decode.codes;  /* codes state */
  96
  97   /* copy input/output information to locals (UPDATE macro restores) */
  98   LOAD
  99
 100   /* process input and output based on current state */
 101   while (1) switch (c->mode)
 102   {             /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
 103     case START:         /* x: set up for LEN */
 104 #ifndef SLOW
 105       if (m >= 258 && n >= 10)
 106       {
 107         UPDATE
 108         r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);
 109         LOAD
 110         if (r != Z_OK)
 111         {
 112           c->mode = r == Z_STREAM_END ? WASH : BADCODE;
 113           break;
 114         }
 115       }
 116 #endif /* !SLOW */
 117       c->sub.code.need = c->lbits;
 118       c->sub.code.tree = c->ltree;
 119       c->mode = LEN;
 120     case LEN:           /* i: get length/literal/eob next */
 121       j = c->sub.code.need;
 122       NEEDBITS(j)
 123       t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
 124       DUMPBITS(t->bits)
 125       e = (uInt)(t->exop);
 126       if (e == 0)               /* literal */
 127       {
 128         c->sub.lit = t->base;
 129         Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
 130                  "inflate:         literal '%c'\n" :
 131                  "inflate:         literal 0x%02x\n", t->base));
 132         c->mode = LIT;
 133         break;
 134       }
 135       if (e & 16)               /* length */
 136       {
 137         c->sub.copy.get = e & 15;
 138         c->len = t->base;
 139         c->mode = LENEXT;
 140         break;
 141       }
 142       if ((e & 64) == 0)        /* next table */
 143       {
 144         c->sub.code.need = e;
 145         c->sub.code.tree = t + t->base;
 146         break;
 147       }
 148       if (e & 32)               /* end of block */
 149       {
 150         Tracevv((stderr, "inflate:         end of block\n"));
 151         c->mode = WASH;
 152         break;
 153       }
 154       c->mode = BADCODE;        /* invalid code */
 155       z->msg = (char*)"invalid literal/length code";
 156       r = Z_DATA_ERROR;
 157       LEAVE
 158     case LENEXT:        /* i: getting length extra (have base) */
 159       j = c->sub.copy.get;
 160       NEEDBITS(j)
 161       c->len += (uInt)b & inflate_mask[j];
 162       DUMPBITS(j)
 163       c->sub.code.need = c->dbits;
 164       c->sub.code.tree = c->dtree;
 165       Tracevv((stderr, "inflate:         length %u\n", c->len));
 166       c->mode = DIST;
 167     case DIST:          /* i: get distance next */
 168       j = c->sub.code.need;
 169       NEEDBITS(j)
 170       t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
 171       DUMPBITS(t->bits)
 172       e = (uInt)(t->exop);
 173       if (e & 16)               /* distance */
 174       {
 175         c->sub.copy.get = e & 15;
 176         c->sub.copy.dist = t->base;
 177         c->mode = DISTEXT;
 178         break;
 179       }
 180       if ((e & 64) == 0)        /* next table */
 181       {
 182         c->sub.code.need = e;
 183         c->sub.code.tree = t + t->base;
 184         break;
 185       }
 186       c->mode = BADCODE;        /* invalid code */
 187       z->msg = (char*)"invalid distance code";
 188       r = Z_DATA_ERROR;
 189       LEAVE
 190     case DISTEXT:       /* i: getting distance extra */
 191       j = c->sub.copy.get;
 192       NEEDBITS(j)
 193       c->sub.copy.dist += (uInt)b & inflate_mask[j];
 194       DUMPBITS(j)
 195       Tracevv((stderr, "inflate:         distance %u\n", c->sub.copy.dist));
 196       c->mode = COPY;
 197     case COPY:          /* o: copying bytes in window, waiting for space */
 198       f = q - c->sub.copy.dist;
 199       while (f < s->window)             /* modulo window size-"while" instead */
 200         f += s->end - s->window;        /* of "if" handles invalid distances */
 201       while (c->len)
 202       {
 203         NEEDOUT
 204         OUTBYTE(*f++)
 205         if (f == s->end)
 206           f = s->window;
 207         c->len--;
 208       }
 209       c->mode = START;
 210       break;
 211     case LIT:           /* o: got literal, waiting for output space */
 212       NEEDOUT
 213       OUTBYTE(c->sub.lit)
 214       c->mode = START;
 215       break;
 216     case WASH:          /* o: got eob, possibly more output */
 217       if (k > 7)        /* return unused byte, if any */
 218       {
 219         Assert(k < 16, "inflate_codes grabbed too many bytes")
 220         k -= 8;
 221         n++;
 222         p--;            /* can always return one */
 223       }
 224       FLUSH
 225       if (s->read != s->write)
 226         LEAVE
 227       c->mode = END;
 228     case END:
 229       r = Z_STREAM_END;
 230       LEAVE
 231     case BADCODE:       /* x: got error */
 232       r = Z_DATA_ERROR;
 233       LEAVE
 234     default:
 235       r = Z_STREAM_ERROR;
 236       LEAVE
 237   }
 238 #ifdef NEED_DUMMY_RETURN
 239   return Z_STREAM_ERROR;  /* Some dumb compilers complain without this */
 240 #endif
 241 }
 242
 243
 244 local void inflate_codes_free( /* c, z) */
 245 inflate_codes_statef *c,
 246 z_streamp z )
 247 {
 248   ZFREE(z, c);
 249   Tracev((stderr, "inflate:       codes free\n"));
 250 }